This post may contain affiliate links. Please read our disclosure policy.

As the season shifts to fall, it’s finally soup season. French Onion Soup is a classic fall favorite that’s rich, seasoned with beef broth, jammy onions and red wine, and topped with a decadent cap of melted gruyere cheese. It’s heavenly. So I took those delicious flavors and created this French Onion Steak Salad!

French Onion Steak Salad

While this salad isn’t quite as decadent, the flavors that make French Onion Soup special are all here. The caramelized onions and marinated flank steak will bring the flavors that you’re used to, with a creamy vinaigrette and dusting of gruyere. I love how hearty and savory this French Onion Steak Salad is. It’s perfect for a Friday night in for an elevated dinner, and great for entertaining, also!

French Onion Steak Salad

In a hurry? Save time and pair this recipe with my SideDish Honey Dijon Dressing!

Looking for another delicious salad? Try my Bacon Brussels Crunch Salad!

5 from 4 votes

French Onion Steak Salad

Prep: 45 minutes
Cook: 25 minutes
Total: 1 hour 10 minutes
Servings: 4 people



  • 4 Tbsp. extra virgin olive oil – divided
  • 2 Tbsp. red wine vinegar
  • 1 Tbsp. sherry vinegar – or sub balsamic vinegar
  • 1 heaping Tbsp. Dijon mustard
  • 1 tsp. dried thyme
  • 1 ½ lb. flank steak – cut in half widthwise and patted dry
  • 1 ½ tsp. kosher salt
  • ½ tsp. cracked black pepper


  • 1 Tbsp. olive oil
  • 2 medium yellow onions – thinly sliced about 3 cups
  • ½ tsp. Kosher salt
  • ½ tsp. Freshly cracked pepper
  • 1 tsp. Fresh thyme leaves
  • 2 Tbsp. red wine vinegar
  • 1 Tbsp. water


  • cup extra-virgin olive oil
  • 2 cloves garlic – minced
  • ¼ cup caramelized onions – see above
  • 3 Tbsp. red wine vinegar
  • 2 Tbsp. fresh lemon juice
  • 1 tsp. Honey
  • 2 tsp. Dijon mustard
  • 1 tsp. Fresh thyme leaves
  • Pinch of salt
  • Pinch of cracked black pepper


  • 4 cups thinly sliced lacinato kale
  • 4 oz. baby arugula
  • 1 cup thinly sliced rainbow radishes
  • ½ cup finely grated gruyere cheese
  • Flaky salt – for serving



  • In a small bowl, whisk together 3 tablespoons of olive oil, red wine vinegar, sherry vinegar, mustard, and dried thyme. Season the steaks generously with salt and pepper, rubbing the seasoning into the meat. Place the steaks in a gallon sized zip-top bag, pour the marinade over the steak, and massage it into them, ensuring they’re evenly coated. Seal the bag, getting any excess air out, and let marinate in the fridge for at least 30 minutes, preferably overnight. Prior to cooking, remove from the fridge and allow to come to room temperature on the counter for at least 30 minutes.


  • In a large sauté pan, heat the oil over medium high heat. Once hot but not smoking, add the thinly sliced onions, salt, pepper, and thyme. Cook uncovered, stirring intermittently, for about 10-12 minutes until the onions are golden and soft. Turn the heat to medium-low, add the vinegar, and scrape off any browned bits. Cook the vinegar off of the onions and continue to sauté until the onions get deeply browned, about 5 more minutes. If the pan becomes dry, add water in tablespoon increments. Reserve ¼ cup of the onions for the dressing and set the rest aside for the salad to assemble.


  • In a wide mouth mason jar, add the oil, garlic, ¼ cup of caramelized onions, red wine vinegar, lemon juice, honey, Dijon, thyme, salt and pepper. Using an immersion blender, place the head of the blender near the bottom of the jar and blend until emulsified and creamy. The dressing will be thick, similar to the consistency of an aioli.


  • Remove the steaks from the marinade, and let any excess marinade drip off. Heat a cast iron skillet over medium-high heat. Add the remaining tablespoon of olive oil to the pan and swirl to coat. Once the skillet is hot by not smoking, add the pieces of flank steak, leaving space in between them to avoid crowding the pan. You may need to do this in batches, depending on the size of your pan and the steaks. Allow the steaks to get a good, hard sear on one side, about 3-4 minutes undisturbed before flipping. Cook for an additional 2-3 minutes, depending on the thickness of your steak, or until the steaks register 125 degrees for medium rare. It will continue to cook while resting. Transfer to a cutting board and allow to rest at least 5 minutes before serving.
  • Slice the steak on the bias, against the grain and drizzle with any juices left in the pan. Season with a pinch of flaky salt.


  • In a large mixing bowl, add the kale, arugula, half of the radishes, and half of the remaining caramelized onions. Add a spoonful of dressing, and using tongs, toss to coat. Since the dressing is thick, this will take about a minute of tossing to get it all evenly coated. Transfer the dressed greens to a large serving platter. Top with the sliced steak, remaining radishes, remaining onions, and the gruyere. Serve with extra dressing on the side. Enjoy!

Nutrition information is automatically calculated, so should only be used as an approximation.

Additional Info

Servings: 4 people

Photography by Eat Love Eats.

Welcome! I’m Alex.

I’m a food lover sharing healthy, simple, delicious, recipes from my kitchen to yours. Here you’ll find lots of Whole30, lots of healthy, and a little indulgence here and there because…it’s all about balance y’all!

Similar recipes

Leave a comment

Your email address will not be published. Required fields are marked *

Recipe Rating


  1. 5 stars
    My family of two has been on a salad kick for the past 3 weeks and it’s important for us to find healthy, hearty salads full of protein. This salad fulfills all our needs and more. The steak marinade is incredible and I could eat the onions by the spoonful. We used a baby spring mix in place of the kale & arugula because that’s what we had on hand and it worked great. Make this salad, you won’t regret it!

  2. Just made this dish and it was AMAZING!!! It’s definitely going on the meal rotation. Thanks again for a delicious dinner recipe!!!